ASTM_G_185_-_06_2012.pdf

Designation:G18506(Reapproved 2012)Standard Practice forEvaluating and Qualifying Oil Field and Refinery CorrosionInhibitors Using the Rotating Cylinder Electrode1This standard is issued under the fixed designation G185;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers a generally accepted procedure touse the rotating cylinder electrode(RCE)for evaluatingcorrosion inhibitors for oil field and refinery applications indefined flow conditions.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1141 Practice for the Preparation of Substitute OceanWaterD4410 Terminology for Fluvial SedimentG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG5 Reference Test Method for Making Potentiostatic andPotentiodynamic Anodic Polarization MeasurementsG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G16 Guide for Applying Statistics to Analysis of CorrosionDataG31 Guide for Laboratory Immersion Corrosion Testing ofMetalsG46 Guide for Examination and Evaluation of Pitting Cor-rosionG59 Test Method for Conducting Potentiodynamic Polariza-tion Resistance MeasurementsG96 Guide for Online Monitoring of Corrosion in PlantEquipment(Electrical and Electrochemical Methods)G102 Practice for Calculation of Corrosion Rates and Re-lated Information from Electrochemical MeasurementsG106 Practice for Verification of Algorithm and Equipmentfor Electrochemical Impedance MeasurementsG111 Guide for Corrosion Tests in High Temperature orHigh Pressure Environment,or BothG170 Guide for Evaluating and Qualifying Oilfield andRefinery Corrosion Inhibitors in the Laboratory3.Terminology3.1 The terminology used throughout shall be in accordancewith Terminologies G15 and D4410 and Guide G170.4.Summary of Practice4.1 This practice provides a method of evaluating corrosioninhibitor efficiency in a RCE apparatus.The method uses awell-defined rotating specimen set up and mass loss or elec-trochemical measurements to determine corrosion rates in alaboratory apparatus.Measurements are made at a number ofrotating rates to evaluate the inhibitor performance underincreasingly severe hydrodynamic conditions.5.Significance and Use5.1 Selection of corrosion inhibitor for oil field and refineryapplications involves qualification of corrosion inhibitors in thelaboratory(see Guide G170).Field conditions should besimulated in the laboratory in a fast and cost-effective manner(1).45.2 Oil field corrosion inhibitors should provide protectionover a range of flow conditions from stagnant to that foundduring typical production conditions.Not all inhibitors areequally effective over this range of conditions so that is1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.05 on LaboratoryCorrosion Tests.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 2006.Last previous edition approved in 2006 as G185 06.DOI:10.1520/G0185-06R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 important for a proper evaluation of inhibitors to test theinhibitors using a range of flow conditions.5.3 The RCE is a compact and relatively inexpensiveapproach to obtaining varying hydrodynamic conditions in alaboratory apparatus.It allows electrochemical methods ofestimating corrosion rates on the specimen and produces auniform hydrodynamic state across the metal test surface.(2-21)5.4 In this practice,a general procedure is presented toobtain reproducible results using RCE to simulate the effects ofdifferent types of coupon materials,inhibitor concentrations,oil,gas and brine compositions,temperature,pressure,andflow.Oil field fluids may often contain sand.This practice doesnot cover erosive effects that occur when sand is